Electricians and cable installers commonly use a device known as a “fish tape” to help install wiring or cable in an empty conduit. The fish tape is typically a stiff metal or plastic tape fed from a reel with a hand crank to push it through the empty conduit until the free end of the tape sticks out the other end of the conduit. A “leader string” (a term which includes string, cord, lightweight wire, or any other equivalent used for the same purpose) is attached to the free end of the tape, which has a built-in string attachment structure such as a hook or clip, and then the installer rewinds the tape until the leader string has been pulled back through the conduit. The exposed end of the leader string is then attached to a wire or cable, and then the other end of the leader string is used to pull the wiring or cable (hereafter “wiring”) back through the conduit.
Experience shows fish tapes to be heavy, difficult to wind and unwind, slow, and tiring to use when long runs of conduit are being wired.